I have forced air, and the heat is blowing cold air. The thermostat keeps jumping from 61 - 65 - 61 - 69 and back to 61 with the blower keep blowing cold air. The blower won't blow at all with the thermostat set to auto but when I switch it to on it will turn on and just blow cold air with it set at 75. The pilot light is lit on the boiler and I have hot water. What is causing the cold air? The Thermostat?

03-06-2013, 01:48 PM

GFrazier

Re: No Heat

The new thermostat did not fix the problem

03-06-2013, 04:36 PM

dj1

Re: No Heat

Check gas supply. If OK, it could be the gas valve, which is a job for a pro.

03-06-2013, 05:06 PM

keith3267

Re: No Heat

If this is a boiler that provides hot water as well as hot air, then either a circulating pump is not working or you have a solenoid that is not working.

03-06-2013, 05:22 PM

canuk

Re: No Heat

[QUOTE=GFrazier;275449]Hi,

I have forced air, and the heat is blowing cold air. The thermostat keeps jumping from 61 - 65 - 61 - 69 and back to 61 with the blower keep blowing cold air. [/QUOTE]Being forced air heating , it's recycled indoor air ( at the inside ambient temperature ) that you are feeling.

[QUOTE]
The blower won't blow at all with the thermostat set to auto but when I switch it to on it will turn on and just blow cold air with it set at 75.
[/QUOTE] With the thermostat set to * Auto* or *On* only controls when the blower turns on.

Set to *On* you are manually turning on the blower to run constantly until you move the swith to *Off* or *Auto*.

In the *Auto* setting -- only when the heat source is fired and reaches a set temperature ( at the heating unit ) is when the blower would turn on to circulate the heated air. At the point when the indoor temperature reaches whatever you set the thermostat is when the blower shuts off -- automatically.

In other words -- turning the switch to *On* won't turn on the heat -- just the blower

[QUOTE]
The pilot light is lit on the boiler and I have hot water.
[/QUOTE]
Is this a hydronic forced air system --- system that uses hot water circulated through a water to air heat exchanger located in an air handler ?
If so, then it sounds as though there's an issue with the water circulation components or the associated controls or possibly some wiring.

[QUOTE]
What is causing the cold air? The Thermostat?
[/QUOTE]While it's possible a thermostat is faulty and can happen from time to time -- more often than not problems are usually elsewhere --- as you found.

No offense , it doesn't sound as though your knowledge of heating systems lends you doing any further troubleshooting.
My advice would be to call a professional to troubleshoot and repair the heating system.